Fabia Monte Carlo 2014

 

My battery I know is not in the best of health, but due to the car not being used so much as late its getting worse, going flat after 2 weeks. So before lashing out on a new battery, I carried out a parasitic current check at the battery, the drain is around 70 mA after the modules shut down. No reliable mV readings being present on the fuses in the internal fusebox. Further investigation points to a 50mA parasitic current on the cable going from fuse 1 of the engine compartment fusebox (alternator fuse) Presumable this current is too high.

 

Questions

1  Is there anything else powered from this fuse?

2  does anyone know what the spec is for alternator parasitic current?

3  Where is the alarm powered from? As I see from another thread when the internal battery starts to fail it can cause high parasitic current as its constantly calling for charge

Michael

1. Not that I can see by scrolling through a few wiring diagrams. Your engine code would be valuable in getting to the correct diagram, as would knowledge of whether or not the car has start/stop.

2. No, but almost certainly wayyyy less than that.  Try disconnecting the LIN connection at the alternator to see if that changes anything.

3. Fuse 20 in the cabin fuseholder appears to be for the alarm horn.

Thanks for the reply, it looks like I made a mistake! The cable I clipped my clamp meter was from fuse 3 (interia), presumably the feed to the 24 hour side of the internal fuse box.

Pulled fuse 20 (alarm) the parasitic current dropped to 30mA, so it looks like a tempory fix. My engine code is CBZBE............ its a 1.2 TSI Tech model not stop/start

 

Michael

PS I found trying to get relible mV readings on the fuses very difficult, not sure if my technique is laking or my meter is at fault, it seemed to range all over the place, in an attempt to to counter this I resorted to shorting the probes before testing, this helped but still left room for for error. this ranging was particulary bad on fuse 20, strange as the fuse was intact?

Variable HR fuse carrier. Another potential cause is the presence of magnetic fields from power lines. I used to wonder why rail signals tech had a 100Kohm shunt across highly sensitive Fluke DVM, till it was demonstrated to me that the 25KV overhead causes deviations and this value was found to provide effective damping and still retain accuracy of reading . Possibly you need slightly higher . e.g. my Fluke dances quite merrily on the bench on mA auto range.

Edited 14 June, 20205 yr by VWD